It is a major new discovery to find that gastropod taxa of the Pomatiopsidae, sub-family Triculinae, tribe Triculini transmit schistosomes infecting man in Asia. Tricula aperta transmits Schistosoma mekongi of the Mekong River; Robertsiellla kaporensis transmits Schistosoma sp. in central Malaysia (Davis, 1979, 1980; Davis and Greer, 1980). Phylogenetic assessments using classical means, cladistic methods, and techniques of multivariate analysis with ordination by nonmetric multidimensional scaling have shown that of 1,000 species of hydrobioid snails (worldwide), the capacity to transmit Asian schistosoma infecting man is restricted to the family Pomatiopsidae, the subfamily Pomatiopsinae, and the tribe Triculini of the Triculinae. The discovery of Robertsiella and the Malaysian schistosome (Davis and Greer, 1980) strengthens my hypothesis on the origin and evolution of Asian Schistosoma involving over 100 million years time and introduction to Asia via the Indian Plate. The direction of evolution is from India to the headwaters of the Mekong and Yangtze rivers and subsequently down evolving river systems (Davis, 1979, 1980). Specific objectives of this proposal are 1) to continue to study nominal species of Tricula and related taxa throughout their ranges (India, Burma, China, continental S.E. Asia, Philippines), 2) to continue to analyze the systematics and ecology of Triculinae of the Mekong River. By invitation of the Institute of Parasitic Diseases, Chinese Academy of Medical Sciences, Shanghai, work will commence in Yunnan, China on the Triculinae of China. Methods will involve detailed anatomy, ecological-microhabitat assessment, paleontological/geological data, zoogeographical analyses, and multivariate and cladistic techniques for phyletic analyses.